P0031 what do I do?

[rhino1616]

Hi

My 2002 protege5 has 92000Km on it & I did a tune up (82000km oil change, transmisson flush, spark plugs, pvc valve, leads..etc), but recently my check engine light came on, I scanned it & it came up P0031 HO2S Heater control circuit low (bank 1, sensor 1). My car is running in perfect condition but Ive noticed Im getting poorer gas milege, about 40km less than average a tank. I'm no mechanic so i need some help

1) Does this mean the oxygen sensor is broken?
2) Do i have to replace it, or can it be cleaned?
3) I saw cheap oxygen sensor on ebay for P5 $23 (probably from China, any good?) or should I buy the more expensive ones?
4) could this be something other than the O2 sensor (air getting in the manifold)

How would I go about fixing this issue, any help would be greatly appreciated.

Thank you

[Doug Tatham]

The 4-wire O2 sensor has a heating element in it so that the engine doesn't have to come up to temperature before it gives a smooth signal.
Global automotive sells one on ebay for about $19.00. I bought one for the front and rear and have had no problems at all. The rear one supposedly doesn't provide much information and should rarely need replacing. The front one will last about 100K miles. It's easy to replace. You may have to use an extractor to remove the screws on the manifold heat shield. Replace the screws with stainless steel screws and use anti-seize on the screws and on the O2 sensor. A crows foot socket (22mm) can remove the O2 sensor and it's a lot cheaper than the special O2 sensor socket.

If you buy from Global, the wires may not be the same color. Ask them for a wire color conversion table.

[TSOPbananaforyou]

You may not need a new sensor.

That code may mean that the car hasn't been warmed up enough for the car to clear it. Do you drive just short distances?

[LordJebus]

You must find and check the sensor. The code relates directly to the condition of heater ckt seen by ecu. Either the ckt in the sensor is done or the harness. Check around the harnesss and wires as they live close to the exhaust. You may want to ohm them out make sure they are good. Dont waste money on a crap sensor, poot in a proper O2 sensor, trust me it will save you in the long run.